Cauvery River System (Kaveri River) – UPSC

• Devotees call the Cauvery River (Kaveri) Dakshin Bharat ki Ganga, the southern Ganga, or simply “the Ganga of the South”.
• Among the rivers of southern India none is held more sacred, and few anywhere in the country are so fully regulated.
  • It drains into the Bay of Bengal, and its dispute is India’s most closely followed inter-State water conflict.

The Cauvery River and Its Basin

Course

• Source: Talakaveri, on the Brahmagiri range near Cherangala village of Kodagu (Coorg) district, Karnataka, at 1,341 m, about 12°25′ N, 75°34′ E. The Coorg country around it is the head of the whole system.
• Length: it runs 800 km from origin to outfall.
  • It flows south-east for 705 km through Karnataka and Tamil Nadu in one common account.
  • The Central Water Commission (CWC) divides the total into 320 km in Karnataka, 416 km in Tamil Nadu and 64 km along their common border.
• Upper course: it falls about 450 m within 8 km of its source, then swings in broad meanders across the Mysore Plateau, at about 750 m.
• Descent: the river narrows from over a kilometre in width above Sivasamudram, then descends the Eastern Ghats in a series of great falls.
  • The plateau of South Karnataka ends and the Tamil Nadu plains begin at the Sivasamudram waterfalls, given as 101 m high in one common figure.
  • At Shivanasamudram the river splits in two and falls 91 m through falls and rapids.
  • The Sivasamudram Falls plunge a total of 100 m and reach a width of 300 m in the rains.
  • Power from these falls, generated from 1902, supplied Mysore, Bengaluru and the Kolar Gold Fields.
• Gorge: the two branches reunite in a wide gorge, the Mekedatu (“Goat’s leap”). The river then marks the Karnataka–Tamil Nadu boundary for 64 km.
• Mettur: at Hogenakkal (Hogennekkal) Falls it turns south into the Mettur Reservoir.
• Plains: the Bhavani joins on the right about 45 km below Mettur, and the river enters the Tamil Nadu plains.
  • The Noyil and Amaravathi join on the right. The river widens over a sandy bed and flows as the Akhanda Cauvery.
• Srirangam: just past Tiruchirapalli district it divides. The northern branch is the Coleroon (Kollidam), and the southern keeps the name Cauvery.
  • The Cauvery Delta begins here. The branches run about 16 km before coming close again to enclose Srirangam Island.
• Grand Anicut: on the Cauvery branch stands the Grand Anicut, attributed to the Chola king Karikala, about the 2nd century AD. Older accounts say the 1st century AD.
  • Below it the branch divides into the Cauvery and the Vennar, which subdivide across the whole delta.
• Delta: south of Cuddalore in Tamil Nadu the river breaks into many distributaries, forming a wide delta known as the “garden of southern India”.
  • It is quadrilateral, about 8,000 sq km, with a nearly straight 130 km front.

Basin

• States: Tamil Nadu, Karnataka, Keralam (Kerala) and the Union Territory of Puducherry.
• Area: about 81 thousand sq km, or exactly 81,155 sq km on CWC’s description, 2.7% of India.
  • Older tables use 87,900 sq km, and the 2019 CWC assessment uses 85,167.
  • Shares: Tamil Nadu 43,856 sq km, Karnataka 34,273, Keralam 2,866 and Puducherry 160.
• Bounded by the Western Ghats on the west, the Eastern Ghats on the east and south, and the ridges separating it from the Krishna and Pennar basins on the north.
• Nilgiris: this offshoot of the Western Ghats runs east to the Eastern Ghats and splits the basin into two natural and political regions: the Karnataka plateau to the north and the Tamil Nadu plateau to the south.
• Physiography: three parts, the Western Ghats, the Plateau of Mysore and the Delta.
• Soils: black, red, laterite, alluvial, forest and mixed.
  • Red soils cover large areas.
  • Alluvial soils fill the delta, the most fertile tract of the basin.
• Land use: agricultural land covers 66.21% of the basin.
• Water: older mean flow is 20,950 million cubic metres, the CWC basin page gives 21,358, and the 2019 CWC figure is 27.67 billion cubic metres.

Regime

• Two monsoons: the river’s defining trait.
  • The Karnataka part gets its rain mainly from the south-west monsoon, and partly from the north-east.
  • The Tamil Nadu part gets good flows from the north-east monsoon.
  • So the upper catchment is watered in summer and the lower catchment in winter, from the retreating monsoon.
• Result: it is almost a perennial river, with comparatively small seasonal swings, well suited to irrigation and hydroelectric power.
• It is therefore among the best-regulated rivers, with 90 to 95 percent of its irrigation and power potential already harnessed.

Tributaries of the Cauvery River

Pattern

• Left bank: the Harangi, the Hemavati, the Shimsha and the Arkavati, with the small Lokpavani.
• Right bank: the Lakshmantirtha, the Kabbani, the Suvarnavati, the Bhavani, the Noyil and the Amaravati.
• Scale: the system has 21 principal tributaries, each with a catchment over 250 sq km.
  • The Shimsha, Amaravathi and Kabini have the largest catchments. The Hemavathi is the longest.
  • The Hemavathi, Kabini and Bhavani contribute the most flow.

• This map’s “Hogenkkal” is Hogenakkal.

Hemavati

• An important tributary of the Kaveri, it rises in the Western Ghats at about 1,219 m, near Ballalarayana Durga in Chikmagalur District of Karnataka.
• It flows through Chikkamagalooru, Hassan and Mysore districts and joins the Kaveri near Krishnarajasagara.
• It is about 245 km long. A large reservoir stands at Gorur in Hassan district.

Shimsha

• It rises at 914 m in the Devarayanadurga hills of Tumkur District, Karnataka.
• Maddur is the major town on it.
• Markonahalli Dam stands across it in Kunigal Taluk.
• It has a waterfall at Shimshapura in Malavalli Taluk, the site of the Shimsha Hydro Electric Project.

Arkavathy River

• This 161 km long river rises at the Nandi Hills of Chikkaballapur district.
• It flows through Kolar and Bangalore Rural districts and joins the Kaveri at Kanakapura, at a spot called Sangama in Kannada.
• It drains into Chikkarayappanahalli Lake near Kanivenarayanapura.
• Chunchi waterfall, near Sangama, draws numerous tourists.
• Two reservoirs store its water: Hesaraghatta (Hesseraggatta) and Tippagondanahalli (T G Halli).

Lakshmana Tirtha

• It rises from Irupu (Iruppu) Falls in the Brahmagiri Range, in Kodagu district, on the border with Wayanad district of Keralam.
• It flows east and joins the Kaveri in Krishna Raja Sagara Lake.
• Ramathirtha is its major tributary.

Kabini

• Also called Kabani and Kapila, it forms in the Pakramthalam hills of Wayanad District, Keralam, where the Panamaram and Mananthavady rivers meet.
• It runs about 240 km and joins the Cauvery at Tirumakudalu Narasipur, a sacred meeting point called Triveni Sangama.
• The Kabini reservoir’s backwaters are very rich in wildlife, especially in summer, when the receding water leaves grassy meadows.
• About two kilometres below the confluence of the Panamaram, it forms Kuruva Island, of 520 acres, with diverse flora and fauna.

Suvarnavathy

• This 88 km long river rises in the Nasrur ghat Range of Karnataka.
• Its catchment covers about 1,787 sq km.
• The Suvarnavathy dam lies near Attigulipura in Chamarajanagar Taluk, about 3 km from the Chikkahole reservoir project.

Noyyal River

• Its original name was Kanchinadi, later changed to that of the place where it drains into the Kaveri.
• It rises in the Vellingiri hills of the Western Ghats in Tamil Nadu.
• It joins the Cauvery at Kodumudi in Erode District, a place also called Noyyal.
• This 173 km tributary once filled 32 interconnected tanks, which stored its water.

Amaravathi

• Also known as Pournami, this 175 km river starts at the Keralam–Tamil Nadu border, at the foot of Manjampatti Valley between the Annamalai and Palni hills, in the Indira Gandhi Wildlife Sanctuary and National Park.
• It runs north through Amaravathi Reservoir and the dam at Amaravathinagar.
• It nourishes farming in Erode District.
• Pollution: near Karur, the river and its basin are used heavily for industrial water and waste disposal. Many textile dyeing and bleaching units have left it severely polluted.

Distributaries of the Cauvery River

Kollidam River

• Also called the Coleroon River, the Kollidam is the northern distributary of the Kaveri in the Thanjavur delta.
• It leaves the main branch at the island of Srirangam and flows east into the Bay of Bengal.
• Its distribution works are at the Lower Anaicut.
• The town of Chidambaram lies on its banks.

Vennar or Vennaaru River

• A distributary in the Kaveri delta, flowing through Thanjavur, Tiruvarur and Nagapattinam districts.
• It begins at the Grand Anaicut, at the eastern end of Srirangam Island, then flows east.
• At Thenperambur dam, north-west of Thennankudi, it splits. The northern branch becomes the Vettar River, and the southern continues as the Vennar.
• North-west of Needamangalam another dam divides it into three branches. The Pamaniyar and Koraiyar start as the two southern ones, and the Vennar continues through the northern.

Arasalar River

• It flows through Tamil Nadu and Puducherry (Pudducherry). It is one of 5 rivers into which the Kaveri splits on entering Thanjavur district from Trichy.
• It branches at Thiruvaiyaru and reaches the sea at Karaikal, east of Akalanganni.
  • Karaikal served as a river port till the 19th century, when yachts and Marakkalam ships of the Karaikal Marakkayar loaded and unloaded goods there.
• Pollution: high nitrate and chromium were reported in 2013, from sewage and industrial activity.
• Seven distributaries feed the Karaikal area: the Nandalar, Nattar, Vanjiyar, Noolar, Arasalar, Thirumalairajanar and Puravadaiyanar.

Development and Regional Role

Floods in the Cauvery Basin

• The basin is fan-shaped in Karnataka and leaf-shaped in Tamil Nadu.
• Run-off does not drain away quickly because of this shape, so no fast-rising floods occur.

Projects on the Cauvery River

• Pre-Plan period: Krishnarajasagar in Karnataka, and Mettur dam and the Cauvery delta system in Tamil Nadu.
• Plan period: Lower Bhavani, Hemavati, Harangi and Kabini.
• Canal command in older figures:
  • Delta canals: about 6,400 km, irrigating about 4 lakh hectares in Thanjavur and Tiruchirappalli.
  • Mettur canals: about 1.2 lakh hectares.
  • Lower Bhavani: about 79,000 hectares.
  • Visvesvaraya Canal from Krishnarajasagar: about 50,000 hectares in Mysore and Mandya.

Industry in the Cauvery Basin

• Bangalore lies just outside the basin, though it draws drinking water from the river.
• Important industries:
  • Cotton textiles at Coimbatore and Mysore.
  • Cement at Coimbatore and Tiruchirappalli (Trichinapally).
  • Industries based on minerals and metals.
  • The Salem steel plant and engineering firms in Coimbatore and Tiruchirappalli.

Socio-Economic and Ecological Role

• Economic: the delta is Tamil Nadu’s main rice tract. Canals, tanks and anicuts built over about two thousand years make this one of India’s oldest irrigated landscapes.
• Cultural: it links pilgrim centres such as Talakaveri and Srirangam, and it carried the Chola agrarian economy, whose temples and irrigation works still mark the delta landscape.
• Ecological: the basin holds wildlife refuges such as Kabini’s backwaters and Kuruva Island. Against this stand river pollution, heavy regulation and shrinking delta flows in deficit years.

Cauvery River Disputes

Background

• Early use: Tamil Nadu historically used about 602 TMC of the river’s yield, leaving about 138 TMC for Karnataka until the turn of the 20th century.
• The 1924 agreement: made between the Madras Presidency and Mysore, it ran for 50 years.
  • Mettur dam dates from this phase: the agreement of 1924 allowed it, and the reservoir was completed in 1934.
  • Tamil Nadu could extend its farmland by 11 lakh acres from the existing 16 lakh acres.
  • Karnataka could raise its irrigation from 3 lakh acres to 10 lakh acres.
  • The river thus mainly served farmers in Tamil Nadu.
• Lapse: the accord lapsed in 1974.
  • Karnataka argued that it had restricted farming in its part of the basin.
  • To make up lost ground, Karnataka extended cultivation and built reservoirs.
  • This brought the sharing issue to a head. It now involves Tamil Nadu, Karnataka, Puducherry and Keralam.

Tribunal and Supreme Court

• Tribunal: on Tamil Nadu’s demand, the Union government set up the Cauvery Water Disputes Tribunal (CWDT) on 2 June 1990.
  • It issued an interim order in June 1991.
• Award: the tribunal reported on 5 February 2007. Both Tamil Nadu and Karnataka challenged it.
• Supreme Court: it reserved its order in September 2017 and ruled on 16 February 2018, in a judgment that raised Karnataka’s share by 14.75 tmc ft.

• This map shows the 2007 award. The Tamil Nadu and Karnataka figures changed in 2018, as the table above shows.

Current Status

• Release: Karnataka must deliver 177.25 tmc ft a year to Tamil Nadu, measured at Biligundulu on the State border.
• Machinery: the Cauvery Water Management Scheme, notified on 1 June 2018, created the Cauvery Water Management Authority and the Cauvery Water Regulation Committee.
• Deficit years: in 2023, the Committee and Authority ordered releases of 5,000 cusecs. On 21 September 2023 the Supreme Court refused to intervene and left the matter with these expert bodies.
• Mekedatu: Karnataka’s proposed balancing reservoir-cum-drinking water project, on the gorge named above, is the live quarrel.
  • 13 November 2025: the Supreme Court rejected Tamil Nadu’s application as premature, and said the expert bodies must ensure the water reaches Biligundulu.
  • July 2026: the Union Jal Shakti Ministry told Parliament that the 2018 judgment contains no consent requirement. The 2019 project report has been returned for revision, so the project has no approval yet.

Ganga–Cauvery Link

• Kanuri Lakshmana Rao proposed this link in 1972, with some accounts dating the idea earlier.
  • Plan: a canal of 2,640 km, taking about 60,000 cusecs of Ganga flood water near Patna for about 150 days a year, and lifting it over 450 m to join the Cauvery above the Grand Anicut.
  • Verdict: the Central Water Commission found it economically prohibitive, given its huge pumping power demand.
• The idea returns whenever scarcity sharpens the dispute. The current effort is the smaller Godavari–Cauvery link.

Major Inter-State River Disputes